1. Field of the Invention
The present invention relates to a semiconductor light emitting device using a light emitting diode and the like.
2. Description of the Background Art
In the conventional surface-mount light emitting diode, as shown in FIG. 6, a plurality of light emitting elements 102 are arranged within a concave portion 101 of a package 100, and a plurality of lead electrodes 103 having light emitting elements 102 placed thereon, respectively, are arranged so as to be aligned in the longitudinal direction of package 100. A lead electrode 104 for wire bonding is disposed on the end of package 100 in the longitudinal direction located outside of lead electrode 103. Light emitting elements 102 are placed on different lead electrodes 103a, 103b and 103c, respectively, and the bottom surface of concave portion 101 in package 100 made of resin is exposed between light emitting element 102 and lead electrode 104. The exposed bottom surface of concave portion 101 closely adheres to the mold member (not shown) filled in concave portion 101. Light emitting elements 102 each are connected to the outside electrically independent of each other (for example, see Japanese Patent Laying-Open No. 2004-071675).
In the case of the configuration of the light emitting diode as shown in Japanese Patent Laying-Open No. 2004-071675, when lead electrode 103 is increased in area in order to improve heat dissipation, there is a problem that the light axis of light emitting element 102 may be displaced or light emitting element 102 may fall off. The reason thereof will be explained below. Light emitting element 102 placed on lead electrode 103 is also in contact with the sealing member provided for sealing. This sealing member is different in thermal expansion coefficient from lead electrode 103 made of metal material. This causes a significant difference in the rates of expansion by heating and shrinkage by cooling between the sealing member and lead electrode 103. Consequently, light emitting element 102 may be displaced from lead electrode 103, causing displacement of the light axis of the element or falling off of the element.
Furthermore, lead electrodes 103 and 104 are generally silver-plated. The potential difference between these electrodes and the moisture adsorbed into the surface from the ambient atmosphere cause migration of the silver plating in each of the silver-plated lead electrodes. This also produces a problem that the lead electrodes cause an electrical short circuit leading to malfunctions such as lighting failure of the light emitting element.